1. Field of the Invention
A conveyor belt cleaner is for an endless conveyor belt trained about a pair of rollers and comprises a plurality of independently operable scraper blade assemblies for removing from the conveyor belt abrasive and/or foreign materials. Because of the tendency of the belt to accumulate adhering material, it is commonplace to provide beneath the return strand of the belt a plurality of scraper blades to remove this material.
2. Description of the Prior Art
My U.S. Pat. No. 3,342,312 dated Sept. 19, 1967, discloses a mechanical cleaner assembly mounted underneath the return run or strand of the conveyor belt and subjected primarily to bending and torsional forces. The cleaner includes a plurality of torsion spring or arms, each arm operating independently of the others. One end portion of each torsion spring or arm is fixedly connected to the supporting frame and the other end portion, which is free, is provided with a reversible wiper blade which is engageable with the conveyor belt to clean and wipe the abrasive material therefrom.
U.S. Pat. No. 3,504,786 of Carl G. Matson and the prior art cited therein, utilize coil springs in one form or another along with means for adjusting the spring load whereby the scraper blades on the arms are biased into engagement with the belt.
The Matson U.S. Pat. No. 3,674,131 dated July 4, 1972 discloses and describes a modified conveyor belt cleaner with an elastomer spring as illustrated in FIGS. 6 and 7 thereof. With such a construction, each scraper arm includes a sleeve-like part which embraces an elastomer, torsionally elastic torus that is mountable on a support and constrained or biased against turning about the axis of the torus so that the scraper arm has a bias load thereon. Difficulty has been encountered in installing and operating such conveyor belt cleaner.
In Matson U.S. Pat. No. 3,674,131, the upper and lower semi-circular halves (FIGS. 6 & 7), which are mounted on the tubular support, have a tendency to pivot around the support even though the connecting bolts are tightened as much as possible. The tendency to pivot resulted from the vibration and pressure of the belt.
The Matson U.S. Pat. No. 3,674,131 suggests utilizing spring arms of different lengths so that the wiper or scraper blades thereon do not hit each other and are in effect staggered. When a person attempted to achieve this offsetting or staggering effect, enormous assembly problems were encountered. When the bolts were loosened the entire assembly flopped down as a result of the weight of the arm and scraper blade. Sometimes as many as seventeen of these arms are provided on a single tubular support and to hold them in the proper offset position at the proper distance apart becomes very difficult.
A person encounters great difficulty in adjusting the height of the scraper blade of the cleaner of FIGS. 6 and 7 of U.S. Pat. No. 3,674,131 after it is in position under the belt. A conveyor belt is not always flat where the cleaner engages it and therefore the scraper blades have to be adjusted upward or downward.
With the belt cleaner of FIGS. 6 and 7 of U.S. Pat. No. 3,674,131 two wrenches are required, one for the bolt head 72 and one for the nut 74. As soon as the nut was loosened, the weight of the blade at the end of the arm tended to drop the assembly away from the belt. As a person attempted to use one hand to hold the scraper blade in the proper position, only one hand was free to tighten the nut. The whole bolt tended to turn thereby making it difficult to tighten the individual scraper blade arm assemblies so that they conform to any irregularities in the belt.
When a person obtains a belt cleaner, all the blade arm assemblies are locked in a horizontal plane. The cleaner is then mounted under the conveyor belt and by use of a pressure handle of some type, pivot the blades into contact with the belt. The irregularities of the belt are noted and adjustments are made to the individual springs upward or downward so that each individual blade is in contact with the belt before pressure is applied. This is quite important, for if it isn't done, some blades would be completely worn out before others had even come in contact with the belt. There is sometimes as much as 2 inches of irregularity from a horizontal plane in a wide belt.
The aforementioned prior art structures while generally satisfactory leave room for improvement in the areas of manufacture, economy, ease of assembly and disassembly, and maintenance.